Substituted peroxybenzoic acid bleaching agents



3,75,921 Patented Jan. 29, 1963 tic 3,075,921 SUBEETITUTED PEROXYBENZOIC ACID BLEACHENG AGENTS Peter Brocklehurst, Newcastle-upon-Tyne, and Peter John Pengilly, Stocksiield, England, assignors to The Procter & Gamble Company, Cincinnati, flhio, a corporation of Ohio No Drawing. Filed Feb. 3, 1960, Ser. No. 6,379 Claims priority, application Great Britain Feb. 11, 1959 9 Claims. (Cl. 252-99) This invention relates to detergent compositions having bleaching properties.

Peroxybenzoic acid has been known and used for a long time as an oxidizing agent in preparative and analytical chemistry. Unfortunately, peroxybenzoic acid possesses poor stability, decomposing at the approximate rate of 10% per week at room temperature even when maintained in an isolated state. Undoubtedly due largely to this drawback, it has not been found practicable to utilize peroxybenzoic acid as an industrial oxidizing agent, for example as an industrial bleaching agent. This is particularly unfortunate since peroxybenzoic acid is potentially an excellent bleaching agent and markedly superior to sodium perborate which is a bleaching agent normally used in household washing preparations. Thus peroxybenzoic acid in alkaline solution bleaches tea stained cloth in five minutes at 130 F. to an extent which is only to be achieved in ten minutes at the boil using alkaline hydrogen peroxide of equivalent available oxygen content.

We have now found that certain substituted forms of peroxybenzoic acid possess good stability and can be very usefully incorporated in solid detergent compositions, more particularly compositions which are in the form of powder, flakes or granules.

According to the present invention there is provided a solid detergent composition comprising an active detergent ingredient and a peroxybenzoic acid which is substituted in the benzene nucleus by at least one group selected from nitro-, chloro-, cyano-, lower alkyland lower alkoxy-groups, the substitution being such that the substituted peroxybenzoic acid has a melting point not lower than 50 C.

A wide variety of combinations of the aforesaid substituent groups can be used provided that the substituted acid has a melting point of at least 50 C. It will be appreciated that it is not a general phenomenon that substitution in the benzene nucleus of peroxybenzoic acid imparts stability and it could not have been predicted from information available in the literature that it could be accomplished by the use of certain selected substituents. The precise mechanism by which these substituents increase stability is not clearly established.

While various combinations of the aforesaid substituent groups lead to satisfactory improvement in stability, we prefer that not more than two nitro-groups should be included because of the danger of explosion with the polynitro compounds. Also, because of the difficulty of preparing compounds with a larger number of substituents in the benzene nucleus, we prefer not to have more than three substituent groups (in addition to the peroxy carboxyl group already present).

Table I below is illustrative of the melting points, stability and bleaching effects using various substituents.

Because of technical difficulties involved in obtaining reproducible data of the type described, we do not commit ourselves to the quantitative accuracy of the figures quoted although they are correct qualitatively and are representative of the etfects involved.

Table I Percent Loss of colour Purity, oxygen removal Substrtuent percent M.P per week, from teapercent stained cotton cloth None 1 93. 3 10.0 65 2-methyl l 91. 4 15. l Z-methoxy 1 68. 4 39. 1 3 77.0 44. 5 4-chl0ro 98. 5 0. 1 82 2-nitro- 96. 9 0.3 77 4-methyl 96. 5 0. 1 57 3-chloro 97.3 0.2 81 2,4- dichloro 0. 2 84 3-uitr0 98. 0 0. 3 84 4-methoxy 90. 2 0. 3 6i 4-tert. but 95. 9 0.3 72 S-methyl 93. 0 0. 6 69 4-isopropv 93. 0 O. 5 70 2-chloro 95.0 1.2 57 tcyauo 49. 0 2. 4 89 4-nitro 84. 9 0. 1 89 1 These are included for the purpose of comparison.

The percentage colour removal obtained by sodium perborate used under the same conditions at the same available oxygen content in the bleach bath was 4%.

To determine the stability of the peroxyacids, they are stored in the dark at room temperature in a stoppered bottle, the available oxygen content being determined at the beginning and end and at appropriate intervals during the storage period; the average loss of oxygen per week is then calculated. The available oxygen content is determined as follows:

0.05 gm. of the peroxyacid is weighed into a 250 ml. conical flask and 10 ml. of dioxane is added. When the pcroxyacid is completely dissolved 10 ml. glacial acetic acid and 10 ml. of 10% aqueous potassium iodide solution are added followed by 50 ml. distilled water. The iodine is titrated with 0.025 N sodium thiosulphate solution using thyodene indicator near the end point.

The bleaching power of the peroxyacids is determined by adding sufficient of the peroxyacid to a 0.5% aqueous solution of a commercial heavy-duty synthetic detergent composition containing no other bleaching agent to give an available oxygen content of the solution of 50 parts per million. The pH is adjusted to 9.0 by addition of caustic soda or sulphuric acid as necessary. A 2-inch square of tea-stained cotton is agitated in this solution for 5 minutes at F. and is then rinsed and dried. The reflectance of the cloth is measured by an EEL Reflectance Spectrophotometer.

The percentage colour removal is reflectance of bleached cloth minus reflectance of stained cloth divided by reflectance of desized cloth minus reflectance of stained cloth, and multiplied by 100.

To prepare the tea-stained cloth, a tea solution is prepared byboiling 28 gm. tea in 1 litre distilled water under reflux for one hour and then filtering the solution. A piece of desized cotton cloth, 2 feet x 3 feet, is boiled in this filtered solution for one hour and is then rinsed with 3 cold distilled water until no more colour can be removed and finally dried.

Table I shows that the substituted peroxybenzoic acids with higher melting points have greater stability than those with lower melting points. It is clear that those compounds with melting points above 50 C. are sufficiently stable to be of value as bleaching agents in commercial solid detergent products while those with melting point below 50 C. are too unstable to be of value commercially.

As the peroxyacids are effective bleaching agents in the temperature range 100-175 F., they are eminently suitable for use in textile washing operations such as are carried out in domestic washing machines.

The detergent compositions of the invention may contain as active detergent ingredient, soap and/or synthetic detergents. Particularly suitable are anionic synthetic detergents such as alkyl benzene sulphonates,'alkyl sulphates, fatty acyl isethionates and fatty acyl taurides. The compositions may also contain the customary alkaline builder salts such as pyrophosphates, tripolyphosphates and the normal additives such as solid suspending agents (e.g.

carboxymethyl cellulose), suds boosters (e.g. fatty acid alkylolamides), optical bleaching agents, tarnish inhibitors, colours and perfumes. Such detergent compositions for household washing purposes are generally alkaline, and the incorporation therein of the substituted peroxybenzoic acid is liable to impair the stability of the substituted peroxybenzoic acid. This can be largely overcome by pelletizi-ng the substituted peroxybenzoic acid alone or in admixture with an inorganic neutral or acid salt so as to give pellets of, say, A" diameter. This considerably reduces the relative area of contact between the substituted peroxybenzoic acid and the other ingredients of the washing composition and so renders the substituted peroxy-compound more immune against loss of stability. Moreover, the substituted peroxybenzoic acid may be protected from contact with the other ingredients of the mixture by coating it, preferably in pellet form, with an inert protective material which is removed by solution or melting when the Washing composition is used in normal washing operations.

A suitable protective material is parafiin wax of iodine value (I.V.) 10 or less, and melting point below about 120 F.

Table II below shows the-improvement of stability of 2,4-dichloroperoxybenzoic acid (DC PBA) in a heavy duty synthetic detergent composition which is achieved by pelletizing it, with or without subsequent coating, before mixing with the detergent powder. The table shows the percentage decomposition of the DCPBA, as measured by loss of available oxygen, in detergent powder when stored for three months at 70 F. in a carton.

In all cases the detergent bleach composition Wasproduced by mixing the prepared 2,4-dichloroperoxybenzoic acid with a detergent powder which contained:

23 by weight sodium dodecyl benzene sulphonate 39% by weight sodium tripolyphosphate 7% by weight silicate solids 1% by weight sodium carb oxymethyl cellulose 19 by weight sodium sulphate 3 by weight coconut monoethanolamide 8% by weight water and miscellaneous In all cases the detergent-bleach mixture contained 3.9% by weight of 2,4-dichloroperoxybenzoic acid which is sufficient to give an available oxygen content of 0.3% on analysis.

For those samples which are shown as without silicate, the silicate content of the detergent powder was replaced by sodium sulphate.

In the case where the DCPBA was pelletized with an inorganic salt, the pellets contained by weight DCPBAand 50% by weight inorganic salt. When a wax coating was applied to the pellets the weight ratio of wax i r to pellet was 0.25:1. The wax used had I.V. l0 and melting point -1l0 F.

Table II Percent decomposition in 3 months (1) Unprotected DCPB-A .(one month) 94 (2) =DCPBA /3" pellets 38 (3) DCPBtA /s" pellets-wax coated-no silicate l4 (4) -DCPBA-(NH SO /8" pelletsno silicate l4 (5) DCPBA-NaHSO /8" pellets 24 (6) DCPBA-Na H P o pellets 29 (7) DCPBA-Na SO A3" pellets 22 (8) DCPBA-NaHSQ; /s" pellets-wax coated-mo silicate 9 (9) DCIPBA-Na SO., /s pellets-wax coated 9 The pellets were prepared from the powdered substituted peroxybenzoic acid, or from a mixture of equal parts by weight of the powdered substituted peroxybenzoic acid and the powdered inorganic salt, by means of a tabletting machine producing tablets Ms" diameter and /8" thick.

In those instances where the pellets were coated, 30 parts by weight of the pellets were placed in a polythene lined rotating drum, and a solution of 7.5 parts by weight paraffin wax in 17.5 parts by weight carbon tetrachloride was sprayed on to the pellets while the drum was rotated. A current of air was passed through the drum to carry oif the carbon tetrachloride vapour. After all the wax solution had been sprayed on to the pellets rotation of the drum was continued until the pellets were no longer sticky.

When a detergent powder according to sample No. 7 of Table II, but containing pellets equivalent to 7.9% by weight DCPBA (0.75% available oxygen) based on the total composition, was used in a washing process on tea-stained cotton cloth using the detergent powder at a level of 4 gm. per litre in the washing solution and a cloth to liquor ratio 1:20; the washing being carried out at F. for 5 minutes, the percentage stain removal was 77%.

A comparable test carried out under the same conditions and using sodium perborate at the same available oxygen content in the wash liquor gave only 6% stain removal. In order to obtain 70% stain removal with sodium perborate it was required to boil the wash solution and cloth for 10 minutes.

Peroxybenzoic acid itself may be prepared by reacting dibenzoyl peroxide with sodium methoxide under anhydrous conditions at low temperature (below 0 C.) followed by acidification according to the chemical equation:

dilute HzSOA m1. chloroform. The chloroform layer was dried over sodium sulphate and evaporated under reduced pressure. Yield 42 gm. peroxybenzoic acid of 96% purity.

The nuclear substituted peroxybenzoic acids are obtainable by the same procedure, using the appropriately substituted dibenzoyl peroxides. In Table III below are given the starting materials and yields in thus preparing substituted peroxybenzoic acids.

Table III The substituted dibenzoyl peroxides, used as starting materials, are obtainable from the appropriately substituted benzoyl chloride by the method of Swain, Stockmayer and Clarke (J. Amer. Chem. Soc. 72, 5426 1950) The substituted peroxybenzoic acids may be purified by recrystallisation from chloroform or by sublimation.

As illustrative of purification, by recrystallisation, an impure sample of 2,4-dichloro peroxybenzoic acid was dissolved in the minimum volume of chloroform at room temperature and cooled to -40 C. The precipitated crystals were filtered 01f and dried in a vacuum desiccator and were found to have a purity of 93.4%.

The mother liquor was diluted with an equal volume of petroleum ether (boiling point 40-60" C.), cooled to -80C., filtered rapidly and the crystals dried in a vacuum desiccator to give a purity of 98.1%.

Other peroxyacids which can be purified by the same technique are 4-nitro-, 4-chloro and 4-methyl-peroxybenzoic acids.

To illustrate purification by sublimation, the sample is heated at 4050 C. on a water bath and sublimed under vacuum onto a cold finger (cooled by tap water). This method gave samples of the following percentages of purity:

Percent 4-nitro peroxybenzoic acid 66.9 2-chloro peroxybenzoic acid 93.4 4-methyl peroxybenzoic acid 96.9 4-methoxy peroxybenzoic acid 77.1 2-chloro-4-nitro peroxybenzoic acid 79.4 3-chloro peroxybenzoic acid 98.5 3-methyl peroxybenzoic acid 92.9 4-isopropyl peroxybenzoic acid. 93.0 4-chloro peroxybenzoic acid 95.5

What is claimed is:

1. A water-soluble detergent composition consisting essentially of a solid active anionic synthetic detergent ingredient which is present in sufficient amount to remove soil from textile materials, said solid active anionic synthetic detergent ingredient being selected from the group consisting of alkyl benzene sulphonates, alkyl sul phates, fatty acyl isethionates and fatty acyl taurides; and, a solid substituted peroxybenzoic acid bleaching agent which is present in suflicient amount to provide bleaching activity and is characterized by a stability to de composition in its solid state, said peroxybenzoic acid bleaching agent being substituted in the benzene nucleus by at least one radical selected from the group consisting of nitro, chloro, cyano, lower alkyl and lower alkoxy radicals, the substitution being such that the substituted peroxybenzoic acid bleaching agent has a melting point of at least 50 C.

2. A water-soluble detergent composition consisting essentially of a solid active anionic synthetic detergent ingredient which is present in sufiicient amount to remove soil from textile materials, said solid active anionic synthetic detergent ingredient being selected from the group consisting of alkyl benzene sulphonates, alkyl sulphates, fatty acyl isethionates and fatty acyl taurides; and, a solid substituted peroxybenzoic acid bleaching agent which is present in sufficient amount to provide bleaching activity and is characterized by a melting point of at least 50 C. and a stability to decomposition in its solid state, said peroxybenzoic acid bleaching agent being selected from the group consisting of 2-chloro-, 3- chloro-, 4-chloro-, 2,4-dichloro-, 2-nitro-, 3-nitro-, 4-nitro-, 3-methyl-, 4-methyl-, 4-methoxy-, 4-tertiary butyl-, 4isopropyl-, 4-cyano-, and 2-chloro-4-nitroperoxybenzoic acids.

3. A water-soluble detergent composition consisting essentially of a solid active anionic synthetic detergent ingredient which is present in suflicient amount to remove soil from textile materials, said solid active anionic synthetic detergent ingredient being selected from the group consisting of alkyl benzene sulphonates, alkyl sulphates, fatty acyl isethionates and fatty acyl taurides; and, a solid substituted peroxybenzoic acid bleaching agent which is present in suflicient amount to provide bleaching activity and is characterized by a melting point of at least 50 C. and a stability to decomposition in its solid state, said peroxybenzoic acid bleaching agent being 2,4-dichloroperoxybenzoic acid.

4. A water-soluble detergent composition according to claim 3 wherein the solid active anionic synthetic detergent ingredient is sodium dodecyl benzene sulphonate.

5. A water-soluble detergent composition according to claim 3 wherein the solid active anionic synthetic detergent ingredient is sodium dodecyl benzene sulphonate and the solid 2,4-dichloroperoxybenzoic acid bleaching agent is present in the form of pellets.

6. A water-soluble detergent composition according to claim 3 wherein the solid active anionic synthetic detergent ingredient is sodium dodecyl benzene sulphonate and the solid 2,4-dichloroperoxybenzoic acid bleaching agent is present in the form of pellets, said pellets containing an inorganic non-alkaline salt selected from the group consisting of ammonium sulphate, sodium sulphate, sodium hydrogen sulphate and disodium dihydrogen pyrophosphate.

7. A water-soluble detergent composition according to claim 3 wherein the solid active anionic synthetic detergent ingredient is sodium dodecyl benzene sulphonate and the solid 2,4-dichloroperoxybenzoic acid bleaching agent is present in the form of pellets, said pellets being coated with a paraffin wax having an iodine value of less than 10 and a melting point below about F.

8. A water-soluble detergent composition according to claim 3 wherein the solid active anionic synthetic detergent ingredient is sodium dodecyl benzene sulphonate and the solid 2,4-dichloroperoxybenzoic acid bleaching agent is present in the form of pellets, said pellets containing an inorganic non-alkaline salt selected from the group consisting of ammonium sulphate, sodium sulphate, sodium hydrogen sulphate, and disodium dihydrogen pyrophosphate, and being coated with a parafiin wax having an iodine value of less than 10 and a melting point below about 120 F.

9. A water-soluble detergent composition consisting essentially of (a) a detergent ingredient for removing soil from textile materials, said detergent ingredient consisting essentially of 23% by weight sodium dodecyl benzene sulphonate 39% by weight sodium tripolyphosphate 7% by weight silicate solids 1% by weight sodium carboxymethyl cellulose 19% by weight sodium sulfate 3% by weight coconut monoethanolamide 8% by weight water, and

(b) 3.9% by Weight of (a) of a solid substituted peroxybenzoic acid bleaching agent for providing bleaching activity, said bleaching agent being 2,4-dichl0roperoxybenzoic acid.

References Cited in the file of this patent UNITED STATES PATENTS 1,539,701 Sutherland May 26, 1925 1,950,956 Wilhelm Mar. 13, 1934 2,222,830 Moss Nov. 26, 1940 OTHER REFERENCES Tobosky et al.: Organic Peroxides, Intel-science Pub. Inc., NY. (1954), pp. 79 and 82. 

1. A WATER-SOLUBLE DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF A SOLID ACTIVE ANIONIC SYNTHETIC DETERGENT INGREDIENT WHICH IS PRESENT IN SUFFICIENT AMOUNT TO REMOVE SOIL FROM TEXTILE MATERIALS, SAID SOLID ACTIVE ANIONIC SYNTHETIC DETERGENT INGTEDIENT BEING SELECTED FROM THE GROUP CONSISTING OF ALKYL BENZENE SULPHONATES, ALKYL SULPHASES, FATTY ACYL ISETHIONATES AND FATTY ACYL TAURIDES; AND, A SOLID SUBSTITUTED PEROXYBENZOIC ACID BLEACHING AGENT, WHICH IS PRESENT IN SUFFICIET AMOUNT OT PROVIDE BLEACHING ACTIVITY AND IS CHARACTERIZED BY A STABILITY TO DECOMPOSITION IN ITS SOLID STATE, SAID PEROXYBENZOIC ACID BLEACHING AGENT BEING SUBSTITUTRD IN THE BENZENE NUCLEUS BY AT LEAST ONE RADICAL SELECTED FROM THE GROUP CONSISTING OF NITRO, CHLORO, CYANO, LOWER ALKYL AND LOWER ALKOXY RADICALS, THE SUBSTITUTION BEING SUCH THAT THE SUBSTITUTED PEROXYBENZOIC ACID BLEACHING AGENT HAS A MELTING POINT OF AT LEAST 50*C. 